Composite material has a life cycle much like other materials. Inspection is part of the process used to track the condition of composite materials during its life cycle.
Inconsistencies in the resin of a composite structure may be difficult to detect using nondestructive testing without accompanying inconsistencies in the fibers of the composite. Inconsistencies in the resin of a composite structure may be caused by many sources including, but not limited to, exposure to high temperature for short time periods or moderate temperatures for long periods, lightning strikes and electrical arcing. Structures may also acquire inconsistencies due to the force of a physical impact.
At present, there are no approved nondestructive test methods to assess inconsistencies in the resin of composites, particularly thermally induced resin inconsistencies.
The alterations of the composite structures may not be visible to the human eye. For example, in order to determine whether a composite structure or part may have been subjected to excessive thermal loads, it was necessary to cut sample plugs or sections from regions of the structure or part suspected of having undergone alteration. The material samples were subjected to any of several testing techniques, such as thermal mechanical analysis (TMA) or differential scanning calorimetry (DSC). The removal of sample plugs for analysis was a time consuming and destructive process, which, in the case of commercial aircraft operations, increased maintenance costs and cycle times at maintenance facilities.
Accordingly, there is a need for a method and apparatus for nondestructively inspecting carbon fiber reinforced resin composite structures which overcome the problems discussed above. Embodiments of the disclosure are directed towards satisfying this need.